Quantizing tube



July 1, 1958 A. s. JENSEN ET A1. 2,841,727

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ELECTEOA/ 4/? BY 6:0:6: 14 Gmrr W Am #4 United States Patent QUANTIZING TUBE Arthur S. Jensen, Princeton, and George W. Gray, Lambertville, N. J., assignors, by mesne assignments, to the United States of America as represented by the United States Atomic Energy Commission Application January 26, 1955, Serial No. 484,174

1 Claim. (Cl. 313-68) This invention relates to beam deflection tubes such as a switching or quantizing device, and more particularly to a cathode ray tube wherein the beam is deflected along a line according to the amplitude of an input signal, and outputs are obtained from a plurality of Collector electrodes each corresponding with a non-overlapping range of amplitudes of the input signal.

A quantizing tube for translating a signal of continuously varying amplitude to one varying in a step-like manner is useful in pulse code communications systems, in pulse amplitude analyzing equipment and in signal amplitude analyzing equipments.

It is an object of this invention to provide an improved quantizing tube wherein an electron beam deflected by an input signal rapidly shifts from one collector electrode to another with a minimum of overlapping (cross-talk).

It is another object to provide an improved quantizing tube wherein an electron beam shifts from one collector electrode to another without an interval in between when neither electrode provides an output.

It is a further object to provide an improved quantizing tube having a relatively low-level input, and high-level outputs.

In one aspect, the quantizing tube of this invention comprises an evacuated envelope including an electron gun for generating an electron beam. Means are provided to focus the electron beam and to deflect it along a line in accordance with the amplitude of an input signal applied to the deflection means. An apertured dynode is positioned within the envelope in the path swept by the electron beam with solid portions and apertures located along the line. The solid portions. of. the dynode are coated to provide a large number of secondary electrons when struck by the electron beam. A second dynode positioned behind the apertured dynode is adapted to be struck by electrons which pass thru the apertures in the apertured dynode. A first series of electron multi plying dynodes amplify the secondary emission from the solid portions of the apertured dynode and a second series of electron multiplier dynodes amplify the secondary emission from the second dynode. A plurality of collector electrodes are mounted to collect the electrons from the first electron multiplier and a second plurality of collector electrodes are arranged to collect the electrons from the second electron multiplier. The arrange ment is such that an input signal of the given amplitude causes the electron beam to strike a given solid portion of the apertured dynode with the result that electrons are collected on a corresponding one of the collector electrodes. A slightly higher input signal causes the electron beams to go thru the adjacent aperture in the apertured dynode and strike the second dynode. The secondary electrons resulting are amplified in the second electron multiplier path and produce a signal at the corresponding collector electrode at the end of this path. The apertured dynode, which may be called a separode," causes alternate electron multiplier paths to be employed as the input signal changes in amplitude,

2,841,727v Patented July 1, 1958 These and other objects and aspects of the invention will be apparent to those skilled in the art from the following more detailed description taken in conjunction with the appended drawings wherein:

Figure l is a perspective view showing the general organization of the elements of a quantizing tube constructed according to the teachings of this invention;

Figure 2 is a view of the target assembly of the tube of Figure 1 as viewed looking in the direction which the electrons of the electron beam approach the target, portions' of the target being broken away to reveal interior details;

Figure 3 is a longitudinal sectional view thru the target assembly taken on the line 33 of Figure 2; and

Figure 4 is a longitudinal sectional view thru the target assembly taken on the line 4-4 of Figure 2 with the top part of Figure 2 cut away.

The beam deflection or quantizing tube shown by way of example in the drawings includes an evacuated envelope 10 containing a conventional electron gun 11 provided with the usual focusing electrodes 12. Electrons from the gun 11 pass between centering deflection plates 13, and then between horizontal deflection plates 14. The elements 11 thru 14 are electrically connected to the exterior of the tube by means of lead-ins 15 extending thru the sealed end of the envelope 10 thru connections within the envelope not shown.

A target assembl generally designated 16, is mounted in an enlarged portion of the envelope 10. The target assembly 16 includes a metallic conductive shield or disc 17 provided with a horizontal slit 18 thru which the electron beam passes. The metallic disc 17 prevents electrons from striking undesired parts of the target assembly, and it also provides an electrostatic shield isolating the target assembly from the high frequency signals applied to the horizontal deflection plates 14. The structure designated 19 and 20- s'imilarly provides a window in alignment with the slit 18, and together with the disc 17 provides a convenient method whereby the target assembly may be installed in the envelope it) prior to evacuation and sealing of the envelope. The metallic disc 17, together with members 19 and 20, are electrically connected to a metallic ring seal 21% extending to the exterior of the envelope 10. The orientation of the target assembly 16 (as is clearly shown in Figure 1) is such that the deflecting means 14 cause the beam to sweep back and forth on a line in the center of slot 13 in disc 17. Stated another way, the beam is deflected in a plane normal to the paper in Figure 3.

The target assembly includes a two-path electron multiplier arrangement including a plurality of dynodes and collector electrodes held in position by means of. rods having their ends extending thru apertures in two lating mica end sheets 23 and as. All of the clean 3 are of formed metallic sheets having an arcuate crosssection. The apertured dynode 25 is arranged with solid portions 25b, 25d, 25 25k and 25 all arranged in a straight line in alignment with the slit 18 in the metallic disc 17. A second dynode 26 is positioned behind the apertureddynode 25, and has portions 26a, 26c, 25c, and 261' which are struck by electrons of the electron beam which pass thru the apertures in the apertured dynode 25. All of the dynodes are coated with a suitable material, such as a silver magnesium alloy, so that a large number of secondary electrons are emitted when the dynode is struck by electrons.

The electrons of the electron beam from the gun 11 which strike the solid portions of the apertured dynode 25 cause secondary electrons to be emitted therefrom which are directed to a dynode 27, from which secondary electrons are directed to a dynode 28, from which sec ondary electrons are directed to a dynode 29, and from.

which secondary electrons are in turn directed to one of a plurality of collector electrodes 30b, 30d, 30 30h and 30 Thus, when the electron beam strikes the solid portion 25f of the apertured dynode 25, secondary electrons are collected on the collector electrode 30 Electrons of the electron beam which pass thru an aperture in the apertured dynode 25 strike the dynode 26 causing secondary electrons to be emitted which are directed to a dynode 31, from which secondary electrons are directed to a dynode 32, from which secondary electrons are directed to a dynode 33, and from which secondary electrons are in turn directed to one of a plurality of collector electrodes 34a 34c, 342, 34g and ML Thus, when the electrons of the electron beam strike the portion 26e of the dynode 26, secondary electrons are collected on the collector electrode 34a.

The collector electrodes 30b, 30d, 30 30k and 30 are supported by insulating rods 36 and 37. The collector electrodes 34a, 34c, 345:, 34g and 341' are supported by insulating rods 38 and 39. Each of the collector electrodes 34a thru 34i is provided with individual output leads designated a thru i. The output leads are connected to pins extending thru the glass envelope at the enlarged end of the tube. The dynodes thru 29 and 31 thru 33 are supported by means of conductive metallic rods extending thru apertures in the mica end sheets 23 and 24.

All of the electrodes are spaced from the mica end sheets 23 and 24 by means of conductive spacers having the same cross-sectional shape as the corresponding electrodes and, in the drawing, bearing the same reference numerals as the corresponding electrodes with prime designations added. The spacers are energized with the same biasing potentials as are applied to the corresponding electrodes. The spacers serve to isolate the electrodes from the effects of charges which tend to accumulate on the mica end sheets 23 and 24. Polarizing potentials are applied to the electrodes, and the associated spacers, according to the practice commonly employed in electron multiplier tubes. Polarizing potentials are applied to the electrodes thru pins in the enlarged end of the glass envelope, the pins being in turn connected within the tube to the respective electrodes.

In the operation of the quantizing tube, the electron beam from the gun 11 is deflected by horizontal deflection plates 14 by an amount varying with the amplitude of the input signal applied to the deflection plates 14. The lowest amplitude input signal may, for example, cause the electron beam to pass thru the aperture in the apertured dynode 25 and strike the area 26a of the dynode 26. The series of electron multiplying dynodes 31, 32, and 33 then cause a relatively large number of electrons to strike the collector electrode 34a, and provide an output signal on the output lead a.

When a slightly higher amplitude input signal is applied to the deflection plates 14, the electron beam will strike the portion 25b of the apertured dynode 25. The series of electron multiplying dynodes 27, 28 and 29 then cause a relatively large number of electrons to strike the collector electrode 30b to provide an output on output lead b. Similarly, a still larger input signal applied to the deflection plates 14 causes the electron beam to strike the portion 260 of the dynode 26 with CTl the result that an output is provided on the output lead 0 of collector electrode 34c. It is apparent that higher and higher input signals applied to the deflection plates 14 cause the successive output leads to be successively energized. The quantizing tube illustrated in the drawing includes ten collector electrodes and thus provides for the quantizing of an input signal into ten discrete non-overlapping ranges. Of course, any desired number of quantizing ranges could be provided by employing an appropriate number of apertures in the apertured dynode 25 and a corresponding appropriate number of collector electrodes. If a very large number of outputs are desired, the dynode 26 may in turn be apertured, and an additional series of electron multiplier electrodes and collectors provided so that there are three electron multiplier paths.

It will be noted that when the electron beam is deflected from the portion 26a of the dynode 26 to the portion 26b of the apertured dynode 25, that there is no dead space between the two portions which would result in the absence of output signal during the transition. Therefore, the speed with which a transition is made from one output to the next adjacent output is limited only by the cross-sectional size of the electron beam. By employing a very sharp beam in the plane of the apertured dynode 25, a more rapid transition is obtained than has previously been possible. An output is always obtained from one or another of the collector electrodes, and the interval during which two adjacent output electrodes are energized is reduced to a minimum.

By the arrangement including two electron multiplier paths, there is provided a quantizing tube capable of operation with a relatively low-level input signal, and providing a plurality of quantized high-level outputs.

What is claimed is:

A quantizing tube comprising, an evacuated envelope including means to generate an electron beam, means to deflect said beam along a line, an apertured dynode having solid portions and apertures located along said line, a second dynode positioned to be struck by electrons of said beam which pass thru said apertures, a first series of electron multiplier dynodes arranged to amplify the secondary emission from said solid portions, a first plurality of collector electrodes each corresponding with one of said solid portions and positioned to collect elec trons from the last of said first series of multiplier dynodes, a second series of electron multiplier dynodes arranged to amplify the secondary emission from said second dynode, a second plurality of collector electrodes each corresponding with one of the apertures in said apertured dynode and positioned to collect electrons from said second series of electron multiplier dynodes, and a conductive shield positioned between said deflecting means and said dynodes, said shield being provided with a slit in alignment with said line.

References Cited in the file of this patent UNITED STATES PATENTS 2,173,193 Zworykin Sept. 19, 1939 2,458,539 Soller Jan. 11, 1949 2,563,482 Nelson Aug. 7, 1951 2,629,011 Graham Feb. 11, 1953 

